It was earlier blamed for the deaths of 27 people in a north-eastern village.

Residents said gunmen had shot dead farm workers in Chikongudo, set fire to nearly all the homes there and stolen food in an attack on Wednesday night. The assailants stormed the village in cars and motorbikes, a trademark of Boko Haram, the residents added.

It came a day after twin bombings killed 122 in the central city of Jos. The authorities suspect Boko Haram of being behind them, but there has so far been no claim of responsibility from the group.

On Wednesday, Nigeria's permanent representative, U Joy Ogwu, said: "The important thing is to attack the problem, and that is terrorism."

The BBC's Barbara Plett Usher in New York says Boko Haram's links with al-Qaeda have come under scrutiny.

Reports quoting a draft UN document said its members had received training from al-Qaeda affiliates and fought alongside them in Mali.

Protests

Boko Haram, which has killed thousands of people in Nigeria through a wave of bombings and assassinations since 2009, is fighting to overthrow the government and create an Islamic state.

The government's failure to prevent attacks since launching an offensive against Boko Haram a year ago has triggered widespread anger.

On Thursday, protesters demanding the return of the schoolgirls snatched from their classrooms in the north-eastern town of Chibok and taken hostage five weeks ago were prevented from reaching the presidential villa in the capital, Abuja.